Mesa is a software library for 3D computer graphics that provides a generic Khronos-compliant OpenGL implementation for rendering three-dimensional graphics on multiple platforms.
Mesa is open source software, released under the terms of the MIT License. It was initially developed by Brian Paul in August 1993, and is still maintained by him today. The project contains many contributions from other people, especially in the area of hardware support.
As of April 2008, it is the only commonly known, fully open source implementation of OpenGL which is continually updated to support the latest OpenGL specification. It is widely used, most importantly by the X.Org implementation of the X Window System, where it serves as the OpenGL core for the open source X.Org/DRI OpenGL drivers. X.Org provides the essential functionality used by most graphical applications which run on Unix-like platforms such as Linux.